diff --git a/arch/arm/src/stm32/stm32_rtc_lowerhalf.c b/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
index a9f90304e6..20275ee921 100644
--- a/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
+++ b/arch/arm/src/stm32/stm32_rtc_lowerhalf.c
@@ -617,13 +617,30 @@ static int stm32_setrelative(FAR struct rtc_lowerhalf_s *lower,
 static int stm32_cancelalarm(FAR struct rtc_lowerhalf_s *lower, int alarmid)
 {
 #ifdef CONFIG_STM32_STM32F40XX
-  /* ID0-> Alarm A; ID1 -> Alarm B */
+  FAR struct stm32_lowerhalf_s *priv;
+  FAR struct stm32_cbinfo_s *cbinfo;
+  int ret = -EINVAL;
 
   DEBUGASSERT(lower != NULL);
   DEBUGASSERT(alarmid == RTC_ALARMA || alarmid == RTC_ALARMB);
+  priv = (FAR struct stm32_lowerhalf_s *)lower;
 
-# warning Missing logic
-  return -ENOSYS;
+  /* ID0-> Alarm A; ID1 -> Alarm B */
+
+  if (alarmid == RTC_ALARMA || alarmid == RTC_ALARMB)
+    {
+      /* Nullify callback information to reduce window for race conditions */
+
+      cbinfo       = &priv->cbinfo[alarmid];
+      cbinfo->cb   = NULL;
+      cbinfo->priv = NULL;
+
+      /* Then cancel the alarm */
+
+      ret = stm32_rtc_cancelalarm((enum alm_id_e)alarmid);
+    }
+
+  return ret;
 
 #else
   FAR struct stm32_lowerhalf_s *priv;
@@ -639,6 +656,8 @@ static int stm32_cancelalarm(FAR struct rtc_lowerhalf_s *lower, int alarmid)
   cbinfo->cb   = NULL;
   cbinfo->priv = NULL;
 
+  /* Then cancel the alarm */
+
   return stm32_rtc_cancelalarm();
 #endif
 }
diff --git a/arch/arm/src/stm32/stm32f40xxx_alarm.h b/arch/arm/src/stm32/stm32f40xxx_alarm.h
index bd58643844..5d8d94a197 100644
--- a/arch/arm/src/stm32/stm32f40xxx_alarm.h
+++ b/arch/arm/src/stm32/stm32f40xxx_alarm.h
@@ -93,5 +93,21 @@ struct alm_setalarm_s
 
 int stm32_rtc_setalarm(FAR struct alm_setalarm_s *alminfo);
 
+/****************************************************************************
+ * Name: stm32_rtc_cancelalarm
+ *
+ * Description:
+ *   Cancel an alaram.
+ *
+ * Input Parameters:
+ *  alarmid - Identifies the alarm to be cancelled
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno on failure
+ *
+ ****************************************************************************/
+
+int stm32_rtc_cancelalarm(enum alm_id_e alarmid);
+
 #endif /* CONFIG_RTC_ALARM */
 #endif /* __ARCH_ARM_SRC_STM32_STM32F40XXX_ALARM_H */